3,3-dimethyl-2-(1-propenyl)cyclopropanecarboxylic acid and the ester thereof are important compounds as acidic parts of household agents for epidemic prevention (e.g. JP 54-3933 B). As the method for producing them, a method of using decarboxylation reaction has been known, and for example, 3,3-dimethyl-2-(1-propenyl)cyclopropanecarboxylic acid can be obtained by heating 3,3-dimethyl-2-(2-carboxy-1-propenyl)cyclopropanecarboxylic acid in the absence of a solvent (e.g. J. Chem. Soc., (C), 2739 (1971)). However, this reaction was not enough for industrial method because of the low selectivity.